Activation of low-activity calcium silicate in converter steelmaking slag based on synergy of multiple solid wastes in cementitious material

Abstract

This research aims to activate the low-activity calcium silicate in converter steelmaking slag (CSS) under the synergy of multiple solid wastes, and further increase the dosage of CSS in cementitious materials. In this work, the CSS-based cementitious material (RB) is composed by converter steelmaking slag (CSS), Bayer red mud (BRM), blast furnace slag (BFS), and pulverized coal furnace fly ash (PFA). More importantly, the low-activity calcium silicate in CSS is activated to generate extra CSH gel based on the synergy of CSS, BRM, BFS, and PFA in RB4 (RB4 is an RB with a mass ratio of (Ca + Na)/(Si + Al) is 1.33). Thus, the compressive strength of RB4 in 28 days grows to 53.40 MPa. In parallel, the dosage of CSS in RB is increased to 30 wt%. The main hydration products are CSH gel, ettringite, NASH gel, and CASH gel, which facilitate the performance growth of RBs. The dense microstructure and better pore structure of RB are presented when the mass ratio of (Ca + Na)/(Si + Al) is 1.33. Additionally, the consolidation of harmful elements in RB4 is improved by synergy of CSS, BRM, BFS, and PFA, and their leaching results meet the relevant standards of drinking water. This work is expected to provide an effective method for the synergistic utilization of CSS, BRM, BFS, and PFA in green cementitious materials.